Gear grinding machine



April 28, 1936. E W. WLLER j 2,038,665

GEAR GRINDING MACHI NE Filed March 1, 1932. 4 7 Sheets-Sheet 1 April 28,1936. E. w. MILLER GEAR GRINDING MACHINE "Filed March 1, .1952

7. sheets-Sheet .s

E. w. MILLER GEAR GRINDING MACHINE Filed March l,- 1932 April 28,1936;

Apr-il 28, 1936.

E. w. MILLER GEAR @BINDING MACHINE Filed March l, 1932 '7 Sheets-Sheet 4NN NNN a. N.

April 28, 1936- y E. W. MILLER 2,038,665

v GEAR GRINDING MACHINE Filed March 1, 1952 7 sheets-sheet 5l l/ll/@wfffw'wr y 7 Sheets-Sheet 6 April 28, 1936. E. w. MILLER l GEARGRINDING MACHINE Filed March l, 1952 E. w. MILLER GEAR GRINDING MACHINEl Ap 2s, 1936.

7 sheets-sheet '7 Filed March l, 1952 Patented Apr. 28, 1936 l UNITEDSTATES PATENT OFFICE 2,038,665 GEAR GRINDING MACHINE Applicationr March1, 1932, Serial No. 596,003

21 Claims.

'I'he present invention relates to the art of grinding the tooth facesof gears. Its primary object and accomplishment is to enable gears to beground to completed condition, that is, nished as to all of their teeth,more rapidly than heretofore. Other objects, related to the foregoing,are to enable successive teeth of the gears to be ground in the courseof a continuous traverse of the gear in a circular orbit, withoutreversal of direction andv to index the gear in the course of eachrevolution; to produce a Wider zone of contact between the grindingwheel and the work than has been known heretofore in grinding by thegenerating process; and to vary the speed of revolution of the work inits orbit whereby to give a relatively slow traverse of the work whilegrinding ,takes place and a more rapid traverse during idle periods.ject is to maintain the wheel in correct and true form and position forthe performance of accurate grinding at all times. Still another objectis to accomplish the true and accurate grinding of wide faced gears in asuccession of traverses past the grinding wheel in neighboring paths,with obliteration of any ridges between the cuts made by the wheel insuch successive traverse.

Further objects, uthe means by which they are accomplished, and theessential Ycharacteristics of the invention'- can best be set forthinconnection with a detailed description of specific mechanism containingan embodiment of the invention. In the following speciflcation is givensuch a description of a specific machine and of certain alternativeconstructions for some of the parts of the machine.

In the drawings which illustrate the machine and its modifications thusdescribed,-

Figul is a side elevation partly broken away to show interior parts; I 1

Fig. 2 is a front elevation;

Fig. 3 is a plan view;

Fig. 4 is a longitudinal vertical section taken on line 4-4 of Fig. 5;

Figs. 4a and 4b are detail sectional and eleva- Still another obtionalviews of one of the controlling gears, show- Fig. 10 is a similar viewshowing another modified form of work holder;

- Fig. 11 is'a similar view showing still another work holding andoperating means;

Fig. 12 is a cross section on line I2I2 of Fig. 11. 5

Like reference characters designate the same parts wherever they occurin all the figures.

The detailed description which follows of the specific machine and itsmodifications thus illustrated is for the purpose of explaining thegeneric 10 characteristics ofthe invention with respect to a concreteexample.. but is without intent to limit the scope of protection heresought to such speciiic machine otherwise than as Vmay be required bythe prior art and the purport of the appended 15 claims; my intentionbeing to protect the invenl tion, by such description and claims, notonly specically butalso generically in the full scope. of its essentialnovelty and with the 'benet of all equivalents. 20

The base or frame of the machine thus illustrated comprises a boxlikecasting I5 having a semi-cylindrical horizontal bearing I6 in its upperpart wherein a work carrying turret I'I is rotatably mounted, and avertical cylindrical 25 bearing I8 at the forward end of its lower partwherein the grinding wheel holder and wheel truing mechanism aremounted. The turret I1 is cylindrical -externally with two or morezones, preferably at its opposite ends, separated from one another by anintermediate annular space, tting complementa] internal surfaces of thebearing I6, and has a flange I9 at one end and a retaining disk 20 atthe other end to withhold it 35 from end motion. Itis removably securedin the bearing by a semi-cylindrical cap or cover 2| which surrounds itsupper half and is secured to the base by bolts 22. Flange I9 and plate20 overlap the ends of this cap andthe bearing. 40 Three work spindles23 are mounted rotatably in suitable bearings 2l in the turret,quidistant from, and equiangularly spaced about, the axis of the latter.Preferably there are twobearings fo'r each spindle, alined with oneanother in op- 45 posite end portions of the turret; the intermediatepart of the turret having interior open spaces between the bearingswhichopen into the previously mentioned annular space. This number ofspindles is not an essential detail, for there may be four or morespindles, or two, or one only for certain purposes; but it is aconvenient number. Work arbors 25 are secured in the several spindles byany suitable means and carry gears 26 to be ground. 55

l' the cap 2 i. This internal gear is coaxial with and surrounds theturret; and the turret is formed with recesses which contain the mastergears 21 and permit their protrusion into mesh with the internal gear.The internal gear is wider (longer .end of the other.

in the axial direction) than the master gears 21 in order to permitaxial movement of the spindles asand for a purpose later described. Adevice for eliminating backlash between the control gears is shown inthis connection, on an enlarged scale, in Figs. 4a and 4b; being omittedfrom the assembly drawings, bec'ause of the small scale of thelatter. Itconsists in making the master gears 21 .each in two parts, 2li and 212,of equal length axially and exactly alike as to the number, pitch andform of their teeth, inl tandemarrangement on the work spindle. One ofthese parts, as 21|,

is keyed to the spindle andhas an axial centering n extension 213entering `.a cavity in the adjacent Afclamping screw 214i lpassesthroughl an arcuate hole 215 in one of the gear parts, as 212, into -atapped hole in the other, or there may be a number of such clamp screws,for binding the parts together; and an adjusting screw 2 16is threadedinto one of the parts, as 212, and has an eccentric pin or finger 211contained in a radial slot in the other for effecting easily andaccurately such angular displacement between the parts as Ywill bringtheir teeth into firm bearing on opposite sides simultaneously with theteeth ofthe controlgear 2Q.

The turret. is provided with a surrounding seriesof external gear teeth29 whereby it may be rotated by power delivered from a motor 30, pulleyand belt, or sprocket and chain drive 3l, 32, 33, shaft 35, gear train35, 36, 31, shaft 38, worm or helical gear 39, Worml wheel or helicalgear lill, gear 4l connected with Ml, and an idle gear d2 in mesh with4| and the teeth 29 of the turret. Pulley 33 and gear 35 are both maderast on shaft 34; gears 3.1 and 39 are both made fast to shaft 38, andthe intermediate gear 36 is secured to a shaft 43; these shafts beingmounted parallel to one another in suitable bearings in the interior ofthe frame. As the turret rotates itrevolves the work spindles in aplanetary manner, and' the master gears on such spindles, rolling on thestationary internal gear 28, rotate the spindles about their respectiveaxes.

The grinding Wheel 44 has grinding zones 45 at opposite sides of its rimformed in prole identical with the tooth of an internal gear conjugateto. the gears to be ground. Ordinarily the master gears 21 areidentical, not only in pitch circumference, but also in number and formof teeth with the gears to be ground. Consequently the wheel profile insuch cases is identical with a tooth of the internal control gear 28,and is located with its Work-engaging proiile on the same pitch cylinderas the teeth of the internal gear, as shown best in Fig. 6. To definethis relationship more exactly in words, the grinding wheel is locatedradial to the axis of the internal gear and entirely outside of thecircumference of such gear except as to the limb or portion which passesbetween the teeth of the gears to be ground, and this portion is at thesame distance from. the center, and has the same dimensions in radialsec-v tion, and the same pressure angle, as a tooth of the control gear.Necessarily the grinding wheel is set off to one side of the controlgear far enough to act upon the work.- piece' carried beyond the end ofthe spindle.

The position of the grinding wheel shown in the drawings is designed forgrinding straight spur gears. But it will be obvious to those skilled inthe art that the wheel may be adjusted angularly for grinding helicalgears. When so adjusted, however, the part of its rim nearest to thework still corresponds to the tooth of an internal gear with which thevgear being ground is adapted to mesh.

'I'he Work gears are positioned on their arbors so that their teeth arealined with the teeth of their respective master gears, with the aid ofa work setting attachment shown in Figs. 2 and 3. This attachmentcomprises a bracket ld mounted on a rod l1 which projects forwardly fromone side of the turret bearing i6. A spring pressed plunger rod 48 isslidable endwise in the bracket and has a centering cone dil on its endnext to the orbitof the work pieces. The bracket is clamped adjustablyon rod d1 and is of suitable design to bring the centering point radialto the turret axis and in axial alinement with one of the teeth of thecontrol gear. Normally it is held back out of the way of the work by-across pin 5B on the plunger overlapping the outer end oi the bracketguideway, Vbut when turned so as to allow this cross pin to registerwith a notch 5l in the guide, the centering pin is advanced by itsspring to enter the adjacent tooth space of the work piece.

'I'he grinding wheel is carried by the shaft of a motor 52 (Fig. 2)which is secured to, and may be radially adjustable on, a sleeve 53,called the grinding wheel stool, which ts slidingly in the bearing i8.Being in the position described and being rotated at high speed by'themoton the grinding wheel is adapted to generate and cut to finishedsize the sides of two adjacent teeth in,

the work piece as it is carried past by the rotation of the turret. Theseveral work pieces are 'thus carried past the grinding wheel insuccession, and are caused by the control gear to roll in passing asthough in mesh with a stationary internal gear of which the rim of thegrinding wheel is one tooth.

lt is to be noted that the number of teeth in the control gear 28 is aprime number, or at least is not a multiple of the number of teeth inany master gear, wherefore the work pieces make more, or less, than acomplete rotation, or more or less than a whole number of rotations,about their respective axes `in each revolution of the turret. Therebydifferent teeth of the Work are presented to the grinding wheel witheach revolution. As a work indexing mechanism this device appears toreach the ultimate limit of simplicity, and it is wholly efcient. In anumber of revolutions of the turret equal to the number of teeth on anyone of the work pieces (or a multiple of this number in the case of awide faced gear ground in a number of traverses, three gears arecompleted.

I have made provision for a variable speed of revolution of the turret,so that while each work piece is actually being ground, its traversingmotion will be slow enough for efficient grinding and to avoid danger ofbreaking the abrasive wheel or overheating cr otherwise injuring thework; and the turret will be sneeded un during non-grinding periods.With three spindles, the work pieces are in actual engagement, with thegrinding wheel during a minor fraction only of the revolution of theturret. To effect such variable speed. the gears 35, 36 and 31 are madeas elliptical gears which, in the specific illustration, give an angularspeed ratio of shaft 34 to 38 of 1 to 9, when the gears are in theposition shown in Fig. 1, and of 9 to 1 when turned through 180 and theangular speed ratio between the turret and the gear 39 is 1 to 3. 'I'heacceleration is accomplished by this means with a close approach toharmonic motion.

In case the work pieces are of suchwidth in proportion to the diameterof 'the grinding wheel that they cannot be finished with accuracy in allparts of their width in a single pass, they should be carried past thegrinding wheel a number of times with an increment of axial feed betweentraverses. I have provided for such an axial feed by making the spindles23 movable endwise through their bearings in the turret and by makingthe internal control gear wider than the master gears. The severalspindles are connected by means of a coupling 54 with a slide 55,reciprocatable in a guideway 56 ofthe machine frame in the axialdirection of thespindles. Such slide is conveniently made as a sleevesurrounding a guide rod 51, coaxial with the turret, having an extension58 slidablyv contained in a bearing 59 in the turret. It is confined onthe rod between a shoulder 60 and a nut 6|. Conveniently the coupling 54is composed of two disks detachably bolted together, having openings inwhich the several spindles and the guide rod are contained, and furtherconstructed to hold and grip anti-friction thrust bearings 52 and 53which surround the work spindles and the 'guide rod respectively. Aseparate retainer 54 for the latter thrust bearing is detachably boltedto the outer plate of the coupling. These last described details,however, are optional features which may be varied without departurefrom the essential invention.

The slide 55, which may be called for convenient definition the spindlereciprocator, is fitted non-rotatably in its guideway and is provided onits under side with rackteeth`55 in mesh with a gear segment 66 carriedby a lever 61. 'I'his lever is pivoted on a cross shaft 68 and connected4by a link 69 with an intermediate lever 10 pivoted at 1|. Theintermediate lever in turn is coupled by a connecting rod 12 with acrank pin 13 carried byva disk 14 and adjustable radially thereof in aknown manner by a screw 15. Crank disk 14 is carried by a shaft 16driven through change gears 11, 18 and reduction gearing 19, 89, by amotor 8|. Bysuitable adjustment of the crank Din, and .correlation ofits speed with that of the turret, work pieces of any/width may be fedaxially across the highest part of the grinding wheel in the course ofany desired number of revolutions of the work. For illustratio1 1,`ifthe work vpieces are gears of 30 teeth and of such width that tation ofthe crank occurs'in the opposite directionv while new work pieces arebeing ground. The

axial feed movement so accomplished takes place continuously giving aminute increment I after each tooth of the work has passed the grindingwhee1, but advancing the work through the prescribed fraction of itswidth between successive grinding traverses of the same tooth.

'In order to avoid leaving any ridges, however minute, between the zonesground in successive traverses, I have provided means for superposing arapid back and forth reciprocation of the spindles upon their continuousfeed motion; `This motion ls effected by making the pivot 1| of therocker4 lever -1I) as an eccentric projection on a 'rotatable shaft 82,and rotating said shaft at the desired speed by a motor 83 through abelt and pulley (or sprocket and chain) drive 84, 85, i6. The eccentricmotion of pivot 1| oscillates rock lever 10 additionally about itsconnecting pivot 81 withv the connecting rod 12 as a fulcrum. Thesecondary reciprocation thereby applied to the spindles is preferablyabout equal to (but may be somewhat greater or less than) the length ofthe continuous axial feed between successive grinding traverses of thesame tooth of the work piece.'

Occurring many times while any given tooth of the work is rolling slowlypastv the rapidly rotating grinding wheel, it causes the work to befinished uniformly.

For the grinding of helical gears with the use of the feed motion lastdescribed, the spindle controlling gears (by which I mean the stationaryinternal gear 28 and the master gear 21 on the spindle) are likewisemade as helical gears with the same helix angle or lead as the workpiece; whereby they give the necessary twisting or screwing motion tothe work.

Although the generating principle described requires that the controlgears have a certain relationship, as explained, to the work, this does.

not mean that one machineis necessarily limited to nishing gears of onlyone diameter, pitch, and form of tooth. On the contrary, the machine maybe prepared for finishing a wide variety of different gears by removingthe turret with its work spindles and control gears, and substituting adifferent turret. 'I'his is permitted readily by removing the cap 2| ofthe turret bearing and the -detachable cover of the guideway whichcontains the spindle reciprocator 55. 'I'he spindle recipro- 'eatingmeans, being coupled with the spindles, is

a part of the turret unit. 'I'helarge internal control gear, althoughassociated with this unit, is independent of it and may be separatelyand accurately located in the bearing independently of the turret. Hencethe turret retaining ange 20 is made as a separate plate and thediameter of the turret at the end adjacent thereto, the outside diameterof the teeth 29, and the coupling 54, are all made smaller than theinternal diameter of the gear 28 for withdrawal and insertion endwisethrough the latter; and the bearing and its cap have positioningshoulders 88 for this gear.

A prime essential for the successful operation of the machine is themaintenance of the active or operating faces of the grinding wheel intrue form and correct position. One phase of this invention comprisesmeans for truing the wheel to the desired form and means for adjustingthe wheel and truing means as to position. Attention is directed toFigs. 4, 6 and 'I for explanation of these features. Truing diamonds 89for the two faces of the grinding wheel are set in the inner ends ofscrew threaded holders 90, which may be of known character` mounted andadjustable in a known way in carrier slides 9|. Such carrier slides areindependent of one another and are pressed apart 4by springs 92interposed between them, which springs press and hold externalabutternal control gear and they are located so that all positions ofthe carrier slides are parallel to one another. 'I'he diamonds arelocated and movable in an axial plane of the grinding wheel, but

at the opposite side of the grinding wheel axis from the work.

The templets or formers are set transversely in cylindrical holders bars91, 91, which bars in turn are set into complemental sockets in a mainholder 98 which fits the interior of the grinding wheel stool 53. Themain holder is made of two parts separated from one another on a medianplane,

- and fastened together detachably by bolts 99.

Guideways I 00 are provided in each of the halves of this holder leadinginward from the cleavage plane, in which the carrier slides for thediamonds are contained and into which the cam ends of the .formersproject. A spring 0| is connected to each carrier slide, being coupledat one end to a pin |02 on the slide and at the other end to a pin |03set into thermain'holderacross the carrier guideway. These springsnormally withdraw the diamonds outside of the circumference of thewheel. The carrier slides rest on the upper end of a plunger I 04 whichpasses through, and is movable endwise in, guides |05, and bears at itslower end on the. short arm |06 of a treadle lever |01. The operator, bypressing on the treadle the concave zone of the wheel.

and releasing it, may thus at will traverse the truing diamonds acrossthe faces of .the'grinding wheel. The springs |0| previously Ymentionedhold the carrier slides against the plunger and insure withdrawal of4the diamonds beyond 'the rim of the grinding wheel when the pedal isreleased.

One or both of the formers Afor each of the carrier slides may beadjusted for minor correction of the path in which the truing diamondtravels. In the illustration the upper abutment, 95, of each pair isthus adjustable, although it is to be understood that the abutment 96,or both of them, may be, as well. As here shown, a cylindrical step 95|is set crosswise in the` bottom of the slot in the holder bar 91 whichreceives the former 95,

the latter being notched in its under edge to bear on said step. Twoadjustable screws 952 and 953 are set in the end of the bar to bear onthe upper edge jf-theo former at respectively opposite sides of a linepassing through the step from edge to edge ofthe former. By withdrawingeither of the screws and setting.up the other, the former may be tiltedabout its step bearing through a small angle so as to shift theinclination of its guiding face, as needed to correct or modify, withinlimits, the curvaturelgiven by the diamond to To state in words ageneric characteristic of the truing of which one embodiment is shown inthe drawings, it maybe remarked that `the formers'of each pair 'are setin a tandein arrangement. lengthwise of the adjacent carrier slide, orof the directions in which such slide is moved in truingthe wheel; andthat the guiding faces of the two formers of a pair are on relativelythe same ends of the formers and .divergein relamove and transversealsol to the wheel.

'ditional increment of motion.

ables them to tively the same directions from a straight line tangent tothe guiding faces, or equally, a straight line joining the two coactingabutments of the carrier slide. The distance apart of correspondingformers'for the two slides is related 'to the width of the slides insuch manner that the two diamonds 89, 89 face each other across anintermediate space in an alinement transverse to the paths in which thediamonds are constrained to 'I'he distance apart of the diamonds andtheir proper relationship toa radial plane of the turret is of coursedetermined by adjusting the screw threaded holders 90 in the carrierslides.

A third diamond |08, for facing oir' the circmpensate fordiminution of-its diameter caused by truing; and the truing tools are adjustable inthe same direction and through twicev the distance and the change inposition of the wheel. To make these adjustments the grinding wheelstool is movable axially in the bearing I8 and is restrained fromrotation by a key It rests on an anti-friction thrust or step bearing||2 which in turn rests on a screw ||3 threaded through a nut ||4secured to the bottom of the bearing. The screw is connected at one endto, o r formed as, agear I5 in mesh with a worm or helical` gear I|6 ona shaft ||1 which projects to the outside of the base and is adapted tobe rotated by any suitable means, manual or automatic. ,.The main holder98 for the truing tools is in turn slidable endwise in the stool, inwhich it is restrained from rotation by a key ||9. It rests on ananti-friction step or thrust bearing |20 which in turn rests on a screw|2| threaded intoa nut |22, suitably secured t, or made as an integralpart of, the steel 5 3. The screw |2| is coaxial with screw H3 and hasan extension slidingly fitted within the latter and restrained fromrotation therein by a spline or feather |23.

It will-now be apparent that rotation of the screw ||3 moves thegrinding wheel stool bodily with all that is contained`therein orthereon, and the simultaneous .rotation of screw 2 moves the truing toolmain carrier with an adscrews, |3 and 2| have different diameters, thelead of their threads is the same, wherefore the truing tools areshifted twice as far as the wheel in making any adjustment, as is neededto compensate for-both the reduced diameter and the altered position ofthe wheel. Or, considered from a different point of View, the truingattachment is adjustable relatively to the grinding wheel and with thegrinding wlje/l'holder. The

the same absolute direction, ene performed at one time by a justmentsare i specific arrangent here` shown, where both ad- I single means.

The previously mentioned adjustment of the grinding wheel for grindinghelical gears, may

'Although the to compensate for both the reduced diameter beaccomplished by turning the entire stool in its bearing, wherefore thespline or key for vthe stool may be set in a head |24 which is supportedrotatably on the bearing |8, and by rotatation of which the angularsetting of the wheel may be accomplished. Any suitable means, of acharacter already known or which may hereafter be developed, may be usedfor measuring or indicating the angle of adjustment of the head |24, forlocking it when adjusted, and for measuring or indicating theadjustments of the wheel for diameter and penetration across the orbitof the outer side of the work pieces. Such means are indicated in thedrawings, but as they involve in detail nothing new with the presentinvention, they are passed over Without 'specific description.

It will be understood that a further adjustment may be provided forpositioning the wheel to grind other gear elements oi the unitassemblage shown in Figs. 1, I3 and 4, as well as the element 26. Suchan adjustment may be provided for by making the bearing i8 separate fromthe base structure l5 as a part of, or mounted on, a carriage adjustableon guideways parallel to the work spindles, and equipped with a screw,or a rack and pinion, or other mechanism for setting it in position, andwith means for securing it in position. Suitable designs for suchcarriage, adjusting means and securingmeans will be apparent to themechanical draftsman trained in the design of machine tools, from theforegoing description, without need of further illustration in thesedrawings.

Meansv for ooding the work and grinding wheel with a cooling fluid mayalso be provided, and applied by the machine designer according to wellknown and commonly used practices, without need of instruction by thisspecification.

A machine embodying the principles hereinbefore described is capable ofturning out work finished to a high degree of precision and a ccuracy,with great rapidity. The formation of the grinding wheel with theprofile of an internal gear tooth affords in principle the maximum widthof grinding engagement and conduces to smoothness and continuity of thesurface generated by the rolling traverse of the work. The continuousrotation of the work always inA the same direction in a circular orbitavoids the lost motion, lost time, and high expenditure of powerincident to the operation of a reciprocating or vibrating work holder.This characteristic, together with the variable speed i'actor, whichslows down the work during the fraction of its travel while it isengaged with the grinding wheel, enables the rotation of the turret tobe performed at a relatively high speed in terms of revolutions pe'rminute. For instance, it is feasible to rotate the tu rret at as high aspeed as 40 revolutions per minute. 'If we assume that there are threework pieces of 30 teeth each in course of grinding and that the teeth ofthese gears have a length requiring four traverses of each past thewheel, then all three will be nished inthe course of 120 rotations ofthe turret, taking place in three minutes; that is, an average of oneminute for each gear. In the case of Aa narrower gear or with a grindingwheel of larger diameter, the work may be completed with fewer traversesof each tooth; while the turret may be made with provisions for carryingmore than three Work piecesj or a higher speed of the turret than 40revolutions per minute may be attained, all of which factors conduce toa still more rapid output.

Changes in detail may be made inthe machine for various purposes. Forinstance, the one shown in Fig. 9 is designed to accommodate a gear |28made integral with a solid shank |21 which cannot'be applied to aspindle and arbor of the type shown in Fig. 4. The spindle 23a is madewith an enlarged tubular vend in which is secured detachably a chuck |28adapted to receive the' shank and grasp the hub portion of the gear.This same gure shows also a varlation in the structure of the turretwhich, instead of ybeing made virtually as a single solid piece, is

. there is room for only one work spindle. Such spindle, shown as beinglike the spindle 23 in Fig. 4, (but which may be like that shown in Fig.9, or of other design), is mounted eccentrically in the turret, and itseccentricity is such as will prmit running of a master gear 21a in meshwith the internal control gear 28h. 'Otherwise the turret and the meansfor reciprocating the spindle may be like those previously described, orof any other suitable design.

Figs. l1 and 12 show adesign of turret adapted to generate helical gearshy the aid of straight spur controlling gears; and also provisions forminimizing any possible errors in the internal control gear. In thisdesign the master gears 21h are withheld from reciprocation with thework spindles by thrust bearings |30 at eitherside on the turret and inthel bore of each a helical guide sleeve |3| is made fast. Complementalguide members |32 and |33 are secured to the spindle.l These guides areof essentially the same character as those shown in the Fellows Patent1,662,109, March 13, 1928, and may be made with either straight orhelical contact edges, the latter giving a. rotary movement to thespindle about its axis as it is moved endwise. As the external mastergear is in this case larger than the gear being ground, a compensatoryrotation is given to the internal control gear 28c so that the workpiece will roll in correct mesh with the imaginary internal gear ofwhich the grinding wheel proiile forms one tooth. Such compensatory ordiier.- ential rotation is. given by providing an external series ofgear teeth |34 on the control gear and interposing between these teethand the gear 42a (which corresponds with the gear 42 shown in Fig. 4) achange gear train |35, |36, |31, of which the last named gear mesheswith theexternal teeth |34. Gear |35 is fast on a shaft |38?! imize anyerrors which may exist in the spacing and form of the control gears.This latter feature may be used without as well as with lthe provisionof helical guides for the work spindle. That is, it may be applied tothe design of Fig. 4

which has no such helical guides, In other rescope of the invention, butwithout setting any limit to such range. Many other changes andvariations in the same and other parts of the machine may be made, allwithin the protection which I claim.

I have described a plurality of electric motors as the prime movers forvarious parts of the machine, and for rotating the grinding wheel. Allof them except the one which drives the grinding wheel are equipped withtheir own speed reducing gear trains which enable them to deliver motionat moderate speeds suitable for the requirements of the machine. but asthey are commercial articles and involve no invention original' with me,I have not attempted to illustrate them in detail. It is to beunderstood also that motion may be derived by belts or other means fromprime movers of other types for operating the machine.

What I claim and desire to secure by Letters Patent is:

1. In a grinding machine, a rotatable and axially movable work spindle,a grinding wheel in position to act upon a work piece mounted on saidspindle, and mechanism for shifting the spindle axially with a motioncompounded of relatively rapid reciprocations and a relatively slowcontinuous travel in the same direction.

2. In a grinding machine having an endwise movablev work spindle,mechanism for shitting said spindle endwise including a lever, motiontransmitting means movable .progressively in the same direction appliedto 'a part of said lever, and reciprocation transmitting connectionsapplied to a diil'erent part of said lever, whereby to advance thespindle with a compound movement of reciprocation and continuousadvance.

3. In a lgrinding machine having a relatively movable grinding wheel andwork spindle, of which one of such movements is the cutting travel ofthe wheel, another is a rolling generative movement between the workspindle and wheel, and a third is a relative traverse longitudinally ofthe spindle axis, means for effecting such traverse with a compoundmotion of reciprocation and progress, comprising mechanism including alever, a progressively acting motion transmitter connected to one partof said lever, and a vibrating motion transmitter connected to anotherpart of said lever.

4. Ina grinding machine having a relatively movable grinding wheel andwork spindle, of which oneof such movements is the cutting travel of thewheel, another is a rolling generative movement between the work spindleand wheel, and a third is a relative traverse longitudinally of thespindle axis, means for eiIecting such' traverse with a compound motionof reciprocation and progress, comprising mechanism including a lever, afulcrum for said lever mounted to revolve about an eccentric axis, meansfor so rotating said fulcrum, and a motion transmittermovable in onedirection and coupled to the lever at one side of the fulcrum.

5. A gear grinding machine comprising a base having a bearing, a turretrevolubly mounted in to the orbit of said Work spindle, but whollyexternal to such orbit and arranged with its limb which is nearest tosuch orbit in the position of a tooth of an imaginary internal gearmeshing with a work piece carried by the work spindle.

6. In a gear nishing machine of the character set forth, a stationarybase having a semi-cylindrical turret-receiving cavity and a detachablecap concave internally in complement to the cavity of the base, a turrethaving bearing zones adjacent to its ends iltting within the cavities ofthe base and cap, an internal gear surrounding the turret and securedcoaxialiy therewith between the base and cap, a work spindle supportedrotatably in the end portions of the turret at one side of the axis ofthe turret, a gear on said spindie in planetary mesh with said internalgear, and means for rotating the turret.-

7. In a gear iinishing machine of the character set forth, a stationarybase having a semi-cylindrical turret-receiving cavity and a detachablecap concave internally in complement to the cavity of the base, a turrethaving bearing zones adjacent to its ends fitting within the cavities ofthe base and cap, an internal gear surrounding the turret and securedcoaxialiy therewith between the base and cap, a work spindle supportedrotatably in the end portions of the turret at one side of the axis ofthe turret, said spindle being also movable endwise in its supportingbearings, a gear secured to the spindle between the supporting bearingsthereof in planetary mesh with the internal gear, means for rotating theturret,

and means for moving the spindle endwise relatively to the turret.

8. In a gear finishing machine, a base, a turret rotatably mounted inthe base, a work spindle rotatable and movable endwise in the turret atone side of the rotational axis ofthe turret, a slide external to theturret in line with the axis thereof, a thrust coupling between theslide and Aspindle connected rotatably with each, means for moving theslide in line with the axis o f the turret, means for simultaneouslyrotating the turret, and

a gear on the spindle in planetary mesh with said r internal gear.

9. In a gear finishing machine, a stationary support, a turret rotatablymounted in said support, Work spindles mounted in said turret on axeseccentric and parallel to the axis of the turret, and being movableendwise relatively to the turret, a slide mounted in line with the axisof the turret and having a guiding extension projecting into the turret,means for moving said slide endwise, a coupling having rotatable andthrust-transmitting connection with the slide and spindles respectively,means for rotating the turret, master gears carried by the spindles, anda sun gear mounted on the base coaxialiy with the turret in mesh withsaid master gears.

10.- In a gear finishing machine, a base, a turret rotatably mounted insaid base, a grinding wheel formed in profile at its rim like the toothof a gear, a sun gear mounted on the base coaxial with the turret, awork spindle rotatable in the turret on an axis at one side of theturret axis, a gear on said spindle in planetary mesh with the sun gear,means for rotating the turret, and means for rotating the sun gear withsuch speed. and in such direction as to impart t0 a work piece securedto the spindle and of diierent diameter than said planetary gear, thesame motion as would be imparted to the work piece by rolling it in meshwith a sun gear of different diameter than the aforesaid sun gear.

Il. 1'n a gear finishing machine, a base, a turret rotatably mounted insaid base, a sun gear mounted on the base coaxial with the turret, awork spindle rotatable in the turret on an axis at one side ofthe-turret axis, adapted to carry a gear to be finished, a master gearon the spindle of larger diameter than the gear to be finished, in meshwith the sun gear, means for rotating the turret, and means for rotatingthe sun gear at such different angular velocity than that of the turretas to give the spindle an increment of rotation about its own axissufficient to rotate the gear to be finished in the same manner asthough rolling in mesh with a stationary sun gear.

12. In a. gear finishing machine, a rotatable turret, a work spindlemounted in said turret on an axis parallel to and at one side of theturret axis, a master gear surrounding said spindle, a sun gear coaxialwith the turret in mesh with the master gear, the spindle being movableendwise as well as rotatable, means for rotating the turret, means formoving the spindle endwise independently of the turret and master gear,and guiding means on the spindle and master gear respectively havingcontacting guide faces extending longitudinally of the spindleand'adapted to be of contours such as to give incremental rotation tothe spindle consequent upon its endwise relative motion.

13. In a gear finishing machine, a base, a turret rotatably mounted inthe base, a plurality of work spindles rotatably mounted in the turreton axes beside and parallelr to the turret axis, said spindles beingalso movable endwise relatively to the turret, an internal gearIsurrounding the turret coaxially, a master gear on each spindle in meshwith said internal gear, and confined against endwise movementrelatively to the turret, each master gear and its spindle havingcomplemental guiding means with contact surfaces extendinglongitudinally of the respective spin# dles, means for rotating theturret, and means for moving the spindles simultaneously endwise.

14. In a gear nishing machine as set forth in claim 13, the saidinternal gear being rotatable independently of the turret, and means forrotating said internal gear simultaneously with the rotation of theturret but at a dierent angular velocity. f

15. In a gear finishing machine having means for effecting a relativemotion of generation between a gear to be nished and a rotating 'nishingtool, means for effecting a relative progression in the axial directionof the work, between such tool and the gear being finished, in thecourse of a number of traverses of the work past the tool,

and means for imposing a rapid reciprocating movement upon the memberwhich is so shifted.-

ing wheel in position to act on a work piece mounted on said workholder, one of said holders being movable relatively to the other in adirection such as to transfer the grinding effect progressively alongthe work piece carried by the work holder, a lever connected with saidmovable holder for so propelling it, motion transmitting means movableprogressively in one direction applied to a part of said lever, andreciprocation transmitting connections applied to a different part ofsaid lever, adapted to move said part repeatedly in opposite directionswhile the first named part of the lever is moved continuously in vonedirection.

18. In a grinding machine having means for eifecting a relative rollingmotion of generation d work axis in the course of a number of traversespast the grinding Wheel, whereby to distribute the grinding effectlengthwise over the teeth of the work.

19. In a gear nishirg machine, a turret and spindle combinationcomprising a cylindrical turret having external bearing surfaces,spindles having rotatable bearing engagement in the turret on axeseccentric and parallel to the axis of the turret, master gears on therespective spindles intermediate the ends thereof, the turret havingopen interior spaces containing said master gears' and from whichrtheouter limbs of the master gears protrude, said spindles being movableendwise in the turret andprotruding at one end therefrom, a rodslidingly mounted in the axial line Iof the turret, a coupling rotatablymounted on said rod and having rotatable and thrusttransmittingconnection with the several spindles, and a propeller connected with therod for transmission of endwise movement thereto.

20. A gear grinding machine comprising a grinding wheel lhaving a prolethe same as that of a gear tooth conjugate to the gear to be ground,means for carrying a gear to be ground in an orbit so located that apoint in the toothed zone of such gear intersects the rim of thegrinding cations to the gear in the course of its traverse i l past thegrinding wheel.

21. A- gear finishing machine comprising a supporting structure, aturret rotatably mounted thereon, a. work spindle rotatably mounted inthe turret at one side of the axis of rotation of the turret, adapted torevolve in an orbit a gear tdv be finished, a grinding wheel mounted ina positon substantially radial to suchmorbit so that its rim may enteran interdental space'of the work gear in each traverse of the latterpast the wheel, a sun gear mounted on the supporting structure coaxial,jwith the turret and rotatable about such axis,- a master gear on thework spindle in mesh with said sun gear, and means for rotating the sungear in such direction and at such speed as to cause a work gearsmallerA than the master gear to make rolling .engagement with the rimof the grinding wheel as with the tooth of a stationary sun gear.v

EDWARD W. MILLER.

